In the analysis of solutions by potentiometry, a measuring element is immersed in an analysis solution and the change in potential is determined as a function of an added reagent solution. In this way, potentiometry can be used primarily to conduct acid, base, and redox titrations. As a rule, glass electrodes are used today as the measuring element for pH measurements; such electrodes are readily available on the market.
Because moisture, dust, dirt particles, or aggressive substances can often be present in the area of the electronic parts of the sensor during potentiometric measurements, contactless signal transmission between a sensor element and a corresponding base unit was proposed in EP 1 206 012 A2, so that there are no longer any electrical contact elements—which could corrode or suffer from impaired functionality in some other way as a result of environmental influences at the transition point—between the sensor element and the base unit. According to EP 1 206 012 A2, the measuring element is permanently bonded to a shield housing, in which the electronic unit of the sensor is contained and which is sealed off against external influences. The contactless interface, which is connected to the electronic sensor unit, serves to exchange energy and signals with a corresponding contactless interface in an electronic base unit. The contactless signal transmission is effected by induction, for example.
It has been found that, even in the case of these types of sensor elements, the electronic unit of the sensor is often not protected effectively enough by the shield housing from external influences such as electromagnetic radiation. The dissipation of heat from the electronic sensor unit to the outside and leakage current between the electronic components are also problems which are still not completely solved.
It is therefore the object of the present invention to provide a potentiometric sensor element which is robust, delivers reliable measurement results under almost any set of boundary conditions, and can be manufactured in a well defined, repeatable manner, as well as to provide a corresponding method for producing the potentiometric sensor element.